Date of Award

Spring 2023

Rights

Access is available to all users

Document Type

Thesis

Degree Name

Master of Science (MS) in Biology

Department

Biology

Abstract

Amphibians are a highly diverse class of vertebrates and crucial for natural ecosystems, inhabiting both aquatic and terrestrial environments at different life stages. However, amphibians are facing devastating declines largely due to the disease chytridiomycosis, caused by the fungal pathogens Batrachochytrium dendrobatidis (Bd) and Batrachochytrium salamandrivorans (Bsal). This disease can lead to population declines, biodiversity loss, and species extinction. However, resources to study and mitigate this disease are limited and an opportunity to assist in these efforts has been created in the form of a course-based undergraduate research experience (CURE). Chapter 1 of my thesis used Roger's Diffusion of Innovations framework to evaluate cognitive and affective outcomes in a CURE taught by early adopters across nine North American academic institutions. Chapter 2 of my thesis focused on amphibian pathogen dynamics in eastern Washington. The North American Bsal Task Force’s Surveillance and Monitoring Working Group developed the Student Network for Amphibian Pathogen Surveillance (SNAPS), which is a CURE focused on surveillance and monitoring for the fungal pathogens Bd and Bsal. Cognitive outcomes, or knowledge acquisition, information processing, and reasoning, as well as affective outcomes, such as a belief, system, emotions, and attitudes towards science, were measured. Results from pre- and post-surveys showed that the CURE effectively improved students' selfefficacy towards environmental interests (t (68) = 2.0629, p = 0.04295), content knowledge (t (68) = 11.119, p < 0.001), knowledge of field sampling methods (t (68) = 4.3232, p < 0.001), self-reported content knowledge (t (69) = 11.207, p < 0.001), and self-reported sampling methods (t (68) = 16.092, p < 0.001). Students’ enjoyment of nature and career interest in STEM did not improve from students’ pre- and post-surveys. Across institutions, all objectives analyzed iv were consistent except one: self-reported sampling methods (F (4) = 3.269, p = 0.017). This suggests that the implementation of the SNAPS CURE across multiple universities yields consistent outcomes across 6 out of the 7 objectives measured, regardless of the teaching implementation and location. Changes in students' content knowledge varied based on demographics and class standing, while all other outcomes were consistent showing the SNAPS CURE provides a generally equitable educational experience. Continued research to ensure the equitability across all institutions needs to continue. Positive outcomes that are mostly consistent can encourage faculty to adopt this instructional approach. Chapter 2 of my thesis focused on amphibian pathogen dynamics in Pacific Chorus Frogs (Pseudacris regilla, PSRE) and Columbia Spotted Frogs (Rana luteiventris, RALU), and the correlation with abiotic factors at Turnbull National Wildlife Refuge (TNWR) in Cheney, WA over a four-year period. Using regression and mixed effects models, I analyzed the relationship between sampling date, amphibian species, wetland site, and abiotic factors with the prevalence and intensity of Bd (i.e., Bd zoospore load). The intensity of Bd varied over time for PRSE (overall effect of species on Bd over time: F (3,175) = 126.7, p < 0.001, R2 = 0.656; PSRE: t = - 13.769, p< 0.001), but was consistent over time for the RALU (t = -0.548, p = 0.584). Bd intensity varied across wetlands (F (19,181) = 23.95, p< 0.001, R2 = 0.685) and was influenced by two abiotic factors, pH (t = 10.098, p < 0.001) and water temperature (t = -3.361, p < 0.001), while conductivity and dissolved oxygen did not influence Bd infection. Sampling during hotter days resulted in lower zoospore loads, which is consistent with Bd’s known optimal temperature range. Bd prevalence, or the proportion of infected frogs, over time was higher for RALU (69%) than for PSRE (43%) (F (3,195) = 18.817, p < 0.001, R2 = 0.656), although this pattern varied year to year. In addition, Bd prevalence varied with sampling timepoint, with the highest v prevalence occurring during breeding season, February- June (χ2 (16, 176) = 1114.07, p < 0.001). TNWR exhibited variable Bd prevalence for both amphibians across wetland sites (χ2 (16, 176) = 1114.07, p < 0.001). The prevalence of Bd at TNWR over time was influenced by pH: (χ2 (1) = 70.376, p < 0.001) but not water temperature which did influenced Bd intensity. Additionally, there was no Bsal found at TNWR from 2019-2022. In conclusion, Bd infection dynamics are highly variable at TNWR, thus further temporal and spatial studies are needed to comprehensively understand amphibian populations and their diseases.

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